Download Shure M267 User's Manual

Shure Brothers Incorporated
222 Hartrey Avenue
Evanston IL 60202-3696 U.S.A.
Model M267 User Guide
GENERAL
The Shure Model M267 is a microphone mixer-remote
amplifier specifically designed for professional applications.
The excellent performance, versatility and features of this
complete, compact console make it an ideal choice for studio, remote, or sound reinforcement use, and as an add-on
mixer for expanding existing facilities. It is also ideally suited
for use with audio and video tape recorders to provide multiple microphone inputs.
Features:
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S
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S
S
S
S
S
S
S
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Wide, flat frequency response and extremely low distortion up to +18 dBm output
Extremely low noise and RF susceptibility
Four switchable microphone- or line-level balanced-line
inputs with individual gain controls and low-frequency
rolloff switches. MUMETAL shielding on input transformers
Feedback-type input gain controls for maximum clipping levels and dynamic range
Output switchable for line or microphone level
Built-in switchable peak limiter cuts output overload
distortion, adapts to power supply voltage
LED indicator shows limiter operation or overload with
limiter defeated
Externally adjustable limiter threshold (–4 to +18 dBm)
VU meter calibrated for +4 and +8 dBm with range
switch. Illuminated with ac operation
Ac or built-in battery operation. Noiseless automatic
switchover to battery in case of ac line failure. Battery
test without program interruption
Front-panel headphone level control and monitor jack
drives almost any stereo or mono headphones; output
can be additional unbalanced line feed to drive a tape
recorder or power amplifier
E1999, Shure Brothers Incorporated
27A8376 (SE)
S
S
Direct mix bus for stacking units
S
Low distortion, high-stability tone oscillator for line test
and level checks
S
All connections phased. Line output terminals phaseindicated
S
Compact and lightweight, with rugged, abrasion-resistant case
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Internally selectable 120 or 240 Vac, 50/60 Hz operation
S
Underwriters’ Laboratories Listed and Canadian Standards Association listed as Certified
Automatic muting prevents speaker damage during
turn-on and -off
SPECIFICATIONS
Frequency Response
30 Hz to 20,000 Hz, ±2 dB
Voltage Gain (at 1,000 Hz)
(Outputs terminated: line 600 W, microphone 150 W, mix
bus 3.3 kW, headphone 200 W, tip-sleeve and ringsleeve )
OUTPUT
Inp t
Input
Line
Microphone
Mix
Bus
Low-Impedance
Microphone (150 Ω)
91 dB
41 dB
24 dB
Line
40 dB
–9 dB
–27 dB
Mix Bus
55 dB
5 dB
––
Inputs
IMPEDANCE
Input
Microphone
Line
Mix Bus
Designed
for Use
With
Actual
(Internal)
19 to
600 Ω
1 kΩ
–32 dBV to
–5 dBV∗
(25 mV to 0.56 V)
Less
than10 kΩ
66 kΩ
+20 dBV
3.5 kΩ
3.5 kΩ
+7 dBV (2.2 V)
Input
Clipping Level
∗Depending on input control setting
Printed in U.S.A.
Headphone Output Clipping Level
Outputs
3.16V (+10 dBV) into 200 Ω
IMPEDANCE
Designed for
Use With
Actual
(Internal)
Output
Clipping Level
Any low impedance microphone
input
0.5
–34 dB
(20 mV)
Mix Bus
3.5 kΩ
3.5 kΩ
–8 dBV
(400 mV)
Headphones
8 - 2000 Ω
200 Ω
recommended
400 Ω to
3 kΩ∗∗
+10 dBV
(3.3 V)
600Ω
150Ω
+18 dBm
(6.2 V)
Output
Microphone
Line
Tone Oscillator
1,000 Hz, 1.5% or less THD
Phantom Power
30 Vdc open-circuit, 3.3 kΩ series resistance, input
switches in MIC position only
Operating Voltage
Ac Operation: 120 or 240 volts ±10%, 50/60 Hz,
9.5W, internally switchable[
∗∗Depending on level control setting
Noise
Dc Operation: 27 volts nominal at 15 mA typical nosignal, 18 mA typical at 0 VU (+4 dBm) output with
headphone load; 21.5 volts minimum
Equivalent Input Hum and Noise: –126 dBV (low impedance microphone, 150 Ω - 20-20,000 Hz) into a
600 Ω load at full gain
Battery life: approximately 20 hours with alkaline batteries at +4 dBm output in continuous use; three 9-volt
batteries, type NEDA 1604A (Duracell MN1604 recommended)
Output Noise: –75 dBV (master control fully counterclockwise), –53 dBV (master fully clockwise), (input controls down, 300-20,000 Hz)
Output Hum and Noise: –70 dBV (master control
down), –51 dBV (master control up) (input controls
down, 20-20,000 Hz)
[ Supplied wired for 120 Vac operation (See Service section for 240
Vac operation)
Temperature Range
Distortion
0.35% or less THD from 30 to 20,000 Hz at +15 dBm
output; 0.5% or less IM distortion up to +15 dBm output
level
Operating: –18o to 57o C (0o to 135o F)
Storage: –29o to 71oC (–20o to 160o F)
Common Mode Rejection
Dimensions
65 dB minimum with input of –20 dBV at 100 Hz
See Figure 1
Control Interaction
Less than 1 dB with any control combination
229 mm
(9 in.)
309 mm
(12 5/32 in.)
Overload and Shorting Protection
68.8mm
(2 23/32 in.)
Shorting the outputs, even for prolonged periods, will
cause no damage; microphone inputs will not be damaged by signals up to 3 volts
6.3 mm
(1/4 in. )
Lo-Cut Filters
FIGURE 1
6 dB/octave rolloff at 150 Hz
Weight
Limiter
Net:
Threshold: +15 dBm (line output level; adjustable
from –4 to +18 dBm)
Attack Time:
2.3 kg (5 lb 2 oz)
Packaged: 3.2 kg (7 lb 2 oz)
3 msec typical
Certifications
Recovery Time: 500 msec typical
Peak Indicator
Listed by Underwriters’ Laboratories, Inc., and listed by
Canadian Standards Association as Certified
Lights 6 dB below clipping or at onset of limiter action
2
Input control 1 serves an additional function as the level
control for the tone oscillator when the INPUT 1/OCS 1
switch is in the OSC 1 position.
IMPORTANT: For optimum signal-to-noise ratio, the individual input controls should be operated at as high a setting as possible, consistent with maintaining adequate
control range and input clipping level.
CONTROLS AND CONNECTORS
WARNING
This apparatus must be earthed (grounded)! The
M267 power supply is energized when the unit is
connected to an ac source; disconnect mains
(power) plug from supply when not in use.
Master Gain Control
Inputs
The front-panel control designated MASTER is the master gain control which sets the overall output level of the
mixed sources (including signals applied to the MIX BUS
input).
The four inputs are professional three-pin female XLR
audio connectors located on the rear panel and designated
INPUT 1 through INPUT 4. The inputs are balanced (internal transformer, MUMETAL shielded); pins 2 and 3 are
“hot”, and pin 1 is “ground”. For microphone operation, the
switches labeled LINE/MIC (directly above the input connectors) must be in the MIC position; for line level inputs,
the switches must be in the LINE position. For impedance,
clipping and operating signal levels, refer to the SPECIFICATIONS section.
Limiter
The front-panel LIMITER IN/OUT switch turns on a fastacting, peak-responding limiter circuit that cuts overload
distortion during loud program intervals without affecting
normal program levels. When the LIMITER switch is IN
(operating), the mixer output is limited to approximately
+15dBm. Increasing the individual or MASTER gain controls will increase the average output and the amount of
limiting. The limiter threshold can be reset to any other output between –4 and +18 dBm if desired. With the limiter
switched OUT and tone oscillator activated, adjust INPUT
1 and MASTER level controls to produce an output 0.5 dB
higher than desired. Switch the limiter IN and set the LIMITER THRESHOLD ADJUST control (accessible though
the bottom of the chassis) for the desired level.
Outputs
The rear-panel connector labeled OUTPUT is a professional three-pin male XLR audio connector. With the adjacent LINE/MIC switch in the MIC position, the OUTPUT
connector is used to feed a low-impedance microphone
line or a low-impedance microphone input. With the LINE/
MIC switch in the LINE position, the OUTPUT connector
feeds the line-level input of an amplifier, tape recorder, or
another mixer. The OUTPUT connector is a balanced output with the LINE/MIC switch in either position; pin 1 is
ground, pins 2 and 3 are “hot”, and the connector is in
phase with the corresponding pins of the input connectors.
The front-panel PEAK LED indicator shows limiter operation with the limiter in, and operates when program levels approach overload with the limiter out. The indicator is
much faster than a meter and will be activated by the shortest transient peak, but it remains on long enough to provide
easy recognition.
The rear-panel binding-post connector designated LINE
OUTPUT is in parallel with the OUTPUT connector and
can be used as a line-level output feed simultaneously with
the OUTPUT connector. The terminals are numbered 2
and 3 and are in phase with the corresponding pins of the
input connectors. While the line outputs can be used to
drive various impedance lines, the VU meter is calibrated
for use with a 600 Ω line.
Low-Cut Filters
The low-cut filters provide a low-frequency rolloff to the
response curve as shown in Figure 2. The filters are activated by the LO-CUT IN/OUT switch above each individual
input gain control and can be used individually with each
control to reduce wind noise or undesirable low-frequency
signals such as from condenser microphones or turntable
rumble.
The line output transformer will operate properly with up
to 100 mA dc in the line. This feature permits the use of
standard “dialed-up” telephone lines with dc across them.
(Since a slight distortion increase may occur at high output
levels with maximum dc current, operation with the VU
RANGE switch at +4 dBm is recommended.)
0
Input Gain Controls
–10
The front-panel controls designated 1 through 4 are the individual active gain controls for correspondingly numbered
inputs. Note that the input connectors are located on the rear
panel directly behind their corresponding gain control. The
controls set the preamplifier gain and provide preamplifier
output attenuation. As the gain is reduced, the preamplifier
input clipping level is increased for that channel.
–20
20
50
100
200
500
LOW-CUT FILTER ACTION
FIGURE 2
3
1,000
Mix Bus
Phantom Power
Direct access to the mixing bus is provided through the
rear-panel MIX BUS phono pin jack. This provision is made
primarily to facilitate stacking or “multing” M267s to
achieve additional input capacity without losing any inputs.
With two M267s, for example, the two mixing buses are directly connected, providing two independent master gain
controls and two isolated line amplifiers with eight individually controlled inputs. Since the buses are directly paralleled, a 6 dB drop in gain will occur; and the master or input
controls must be increased to compensate. Noise specifications are not adversely affected by this interconnection.
Mix bus interconnection can also be made with other
Shure mixers, such as the M268, FP42. etc.
The rear-panel PHANTOM OFF/ON switch controls the
application of phantom power for condenser microphones,
such as the Shure SM81 and SM87A, to all inputs. With
the switch on and the rear-panel MIC/LINE switches in the
MIC positions, +30 Vdc is applied to pins 2 and 3 of each
input connection. Series current-limiting resistance is 3.3
kΩ for each input. When using other condenser microphones with the M267, verify that the voltage and resistance requirements are compatible.
Note that the phantom power cannot normally be applied to the inputs with the MIC/LINE switches in the LINE
position.
IMPORTANT: Do not turn the PHANTOM switch on when
using unbalanced low-impedance microphones; objectionable hum will result. Turn off the PHANTOM switch
when condenser microphones are not being used.
Use only high-quality cable. Intermittent shorts between
broken shield wires and balanced conductors will cause offensive noise transients in the system.
VU Meter
The VU meter is factory-calibrated for use with a 600 Ω
terminated line. The VU RANGE switch on the rear panel
selects either a +4 or +8 dBm output at 0 VU meter indication. (This switch changes the meter indication but does
not change the actual output level.) Microphone output
levels are 50 dB below line output. The +4 range is recommended for normal use to provide approximately 14 dB of
headroom from operating level to clipping level.
BATTERY OPERATION AND EXTERNAL POWERING
In addition to ac operation, the M267 can be operated
from an internal battery pack. Current drain is typically 17
mA at +8 dBm output level and typically 15 mA at + 4 dBm.
Battery power is recommended both for remote, on-location operation, and as an emergency backup source in
case of failure of the ac power.
The VU meter is illuminated by two No. 86 lamps operating well under their normal ratings for a life expectancy of
greater than 10,000 hours. The lamps are only lit during
ac operation. Consequently, the illumination serves as a
visual alarm if the ac is interrupted and the unit has
switched to battery.
Access to the battery compartment is provided at the
bottom of the chassis. Three 9-volt alkaline batteries power the M267 at full rated output. Use alkaline batteries for
maximum life. Duracell MN1604A or Eveready 522 are
recommended. Battery life is approximately 20 hours at +4
dBm continuos use. Note that battery operation with phantom power loads and high level headphone monitoring will
increase battery drain.
The VU meter is connected on the primary side of the
output transformer to assure protection from any dc level
on a telephone line.
Headphones
The headphone outlet appears at the front-panel jack
panel designated PHONES. The two-circuit phone jack
will accommodate most stereo or mono headphones. The
output level is sufficient to provide high volume for use in
noisy environments.
With batteries in the battery compartment, the M267 will
automatically and silently switch to battery operation
should the ac voltage fall below a suitable level. If the ac
power fails completely, the VU meter lamps will go out, providing a visual indication of line failure.
Note that the headphone output level is also high
enough to use as an auxiliary unbalanced line feed to drive
a tape deck or a power amplifier.
Battery condition can be determined by using the BATT
CHECK switch on the front panel. Activate the BATT
CHECK switch and observe the VU meter. A new set of
batteries will give about a +2 VU indication. Battery condition is good if the reading is above 0 VU; a lower reading
means that new batteries are required for proper operation. Note that the M267 power switch must be turned on
to check battery condition.
The tip and ring connections of the headphone plugs are
in phase with pin 3 of all input and output connectors, and
with the tip of the MIX BUS jack.
Tone Oscillator
The highly stable, low-distortion tone oscillator provides
for line test and level checks. The oscillator is instantly activated by the front-panel INPUT 1/OSC 1 switch; its level
can then be controlled by the INPUT 1 gain control on the
front panel. The tone oscillator frequency is 1,000 Hz, and
the signal appears on both the line and microphone outputs, as well as the headphone and mix bus connectors.
The oscillator should be switched off (INPUT 1 position)
when not in use.
Telephone Interconnection
When using the M267 connected directly to a telephone
line, check to see whether the local telephone company requires an interface coupler between the M267 and the telephone line. If a coupler is required, make certain the coupler selected and the wiring arrangement are in
compliance with the telephone company regulations.
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3. Locate the voltage selector switch (S201) at the right
rear of the main printed circuit board (Figure 3). Move
SD201 to the 240V position (toward the front panel).
Telephone Line Surge Protection
When using the M267 connected directly to a telephone
line subject to lightning-induced voltage surges, the following commercially available part can be installed across the
LINE OUT terminals to provide additional protection for
output circuit components:
Metal Oxide Varistor, General Electric Co., Type No.
V22ZA1
WHT
BLK
120V
T206
F202
T50/250V
F201
ACCESSORIES
A268R Rack Panel Kit. The Model A268R Rack Panel Kit
includes a 19 in. x 3-1/2 in. (483 mm x 89 mm) precut rack
panel and necessary hardware for rack-mounting the
M267 (with its cover in place and end caps removed) in a
standard 19 in. (483 mm) rack panel.
RKC169 Rack Panel Bracket Kit. The Model RKC169
Rack Panel Bracket Kit enables owners of the Shure A68R
Rack Panel Kit (originally designed for the M67 and M68
Mixers) to rack-mount the M267 with the A68R.
S201
240V
240 V WIRING
FIGURE 3
4. Remove fuse F201 (0.1A, 250V, time lag) and replace
it with the supplied fuse F202 (0.05A, 250V, time lag).
Note that the F202 fuse holder is at right angles to the
F201 fuse holder.
5. Replace the ac line cord (if necessary) with one designed for the 240 Vac source. If the M267 is to be
used outside the U.S. and Canada, local regulations
may require replacing the line cord with one having
wire insulation colors as follows:
SERVICE
WARNING
Voltages in this equpment are harzardous!
Refer servicing to qualified service personnel.
240 Vac Operation
To change the M267 operating voltage from 120 Vac to
240 Vac, follow these steps:
1. Disconnect the M267 from the ac line.
2. Remove the end caps and cover.
“Live” or
“Hot”
Neutral
Earth or
Ground
U.S., Canada
Black
White
Green
Europe
Brown
Blue
Green/
Yellow
6. Replace the cover and end caps, and mark the rear
panel to reflect the new operating voltage.
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PRINTED CIRUCIT BOARDS
COMPONENT SIDE
INPUT TRANSFORMERS T201-T204
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REPLACEMENT PARTS LIST
REFERENCE
DESIGNATION
PART
NUMBER
DESCRIPTION
COMMERCIAL
ALTERNATE
C101,C209,
C219, C227,
C232
86T628
Capacitor, Electrolytic, 5 µF, 25V
Sprague TVA 1303
C115
86L628
Capacitor, Electrolytic, 250 µF, 50V
REFERENCE
DESIGNATION
Sprague
501D227F063PR
PART
NUMBER
DESCRIPTION
COMMERCIAL
ALTERNATE
PL301-PL302
95A8010
Lamp, 6.3V, 0.2A
Sylvania 86
Q201
86A350
Transistor, NPN
Motorola 2N5210
Q202, Q204
86A334
Transistor, NPN
Rohm TIS92
Q203, Q205
86A348
Transistor, PNP
Motorola 2N5087
C201, C204C205, C208
86V628
Capacitor, Electrolytic, 22 µF, 6.3V
Sprague
501D226F016LL
Q206
86A335
Transistor, PNP
Rohm TIS93
C210
C212-C213
86M630
86R630
Capacitor, Electrolytic, 10 µF, 25V
Capacitor, Electrolytic, 68 µF, 25V
Sprague TE 1204
Sprague
501D686F025MN
Q207
86A8302
Transistor, PNP
Motorola TIP30A
R250
46A8016
Potentiometer, 100k
None
C215, C218
86L626
Capacitor, Electrolytic, 470 µF, 35V
Sprague
503D477F035QE
R302, R306,
R310, R314
46B8000
Potentiometer, 100k
None
C216, C222
C221, C229
C223
D209,
D211-D214,
D222-D223,
D226-D229
D210, D217,
D230-D235
86A630
86N630
86S628
86A415
Capacitor, Electrolytic, 5 µF, 35V
Capacitor, Electrolytic, 22 µF, 35V
Capacitor, Electrolytic, 1 µF, 50V
Diode, Silicon, Computer, 75V
Sprague TE1303
Mallory F226KM
Sprague TVA1300
TI 1N4148
R317
46C8000
Potentiometer, 200k
None
R322
46D8000
Potentiometer, 5k
None
S101-S104
55B8008
Switch, Slide, 3PDT
None
S105, S302, S306
55B8007
Switch, Slide, DPDT
None
55B8001
Switch, Slide, DPDT
None
86A404
Silicon Rectifier, 100V, 1/2A
Motorola 1N4002
S106-S107, S301,
S303-S305
S201
55A8035
Switch, Slide, DPDT
Switchcraft EPS1-PC1
D218-D221
D301
86A405
86F422
Diode, Germanium, 30V
Diode,Light-Emitting
RCA 1N48, 1N60
General Instrument
MV5075C
S307
90CB2600 Switch, Pushbutton, SPDT
Switchcraft 953
S308
55A8009
Switch, Slide, 3PDT
None
F201
80F159
Fuse, Slow–Blow, 3AG, 0.1A, 250V
Littlefuse 313000 Series
T201-T204
95B8165
Transformer, Input
None
F202
J1
J2A, B
J101-J104
J105
J301
L101-L113
80C380
95C450
90T2600
95B8011
95B8012
90BJ2600
80A365
Fuse, Time Lag, 0.05A, 250V
Jack, Phono
Connectors, Binding Post
Connector, 3-Pin Female XLR
Connector, 3-Pin Male XLR
Phone Jack
Ferrite Bead Ring
Schurter 034.3104
Switchcraft 3511A
None
Switchcraft Y3FDPC
Switchcraft Y3MPC
Switchcraft L-1128PC
Panasonic
Exc-ELSA35
T205
51E235A
Transformer, Output
None
T206
51A8021
Transformer, Power
None
U201
86B808A
Integrated Circuit, Quad Op Ampl
(Selected for NF)
Raytheon RC4156N
U202
86A8908
Opto-Isolator
None
U203
86A811A
Integrated Circuit, Dual Op Ampl
Raytheon RC4559NB
U204
86A806A
Integrated Circuit, Quad Comparator
Raytheon LM339DB
M1
RKC170
(95A8214)
Meter, 190 µA
None
U205
86A811A
Integrated Circuit, Dual Op Ampl
Raytheon RC4559NB
U206
86A803
Integrated Circuit, Dual Op Ampl
Motorola MC1458C-P1
90A8028
90A8029
90A8027
65A8008
Knob, MIC 1-4, MASTER
Knobs, PHONE
Cover, Battery
End Cap
U207
86B8930
Integrated Circuit, Voltage Regulator
National Semiconductor
LM317AT
W1
90A8045
Line Cord, AC
None
MP1-MP5
MP6
MP7
MP8-MP9
None
None
None
None
Parts listed as RKC Kits should be ordered by that kit number.
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